A scheme is proposed for control of multi-body, multi-input and multi-output nonlinear systems with joint backlash, flexibility and damping, represented by a gun turret-barrel model which consists of two subsystems: two motors driving two loads (turret and barrel) coupled by nonlinear dynamics. The key feature of such systems is that the backlash is between two dynamic blocks. Optimal control schemes are employed for backlash compensation and nonlinear feedback control laws are used for control of nonlinear dynamics. When one load is in contact phase and the other load is in backlash phase, a feedback linearization design decouples the multivariable nonlinear dynamics so that backlash compensation and tracking control can be both achieved. Nonlinear zero dynamics systems caused by joint damping are bounded-input, bounded state stable so that feedback linearization control designs ensure that all closed-loop signals are bounded and asymptotic tracking is achievable. Simulation results verify the desired system tracking performance.